The present invention relates generally to a direct drive transmission in which helical gear sets divide and share input power between and among a multiplicity of intermediate gears to ultimately drive an output gear set, and wherein the loading on the intermediate gears is continuously mechanically balanced to provide uniform driving forces to the output gearset.
1. Field of the Invention
The power transmission industry constantly seeks a way to transmit large loads through small systems. However, in the absence of the use of exotic, high cost alloys, the design and construction of direct drive transmissions are often limited as to size by virtue of the particular application and, accordingly, limited as to the load they can effectively transmit.
One way to reduce the overall size of the transmission is to divide, or split, the load carrying capacity of any given system into multiple paths defined by smaller load carrying elements, which would then permit a reduction in the size of the gears needed per element to transmit a design load. Then, by select spacing and positioning of the elements, the overall size of the transmission is easily reduced.
As is well known, however, when multiple load carrying elements are receiving power from an input source for delivery to an output, whether it be in a step up or step down mode, there is an opportunity, indeed, likelihood, for imbalance between such elements which tends to accentuate wear and create an imbalance at the output end, even creating damaging harmonics, all of which tends to defeat the purpose of dividing the input power.
It will be appreciated that an unbalanced application of power, wherever it may occur in a transmission, inevitably results in uneven wear in the gearing and cyclic, or otherwise erratic, power output which, if not quickly ameliorated, will exacerbate the damage to the transmission itself, as well as any equipment to which it is drivingly connected.
2. Overview of the Prior Art
The concerns addressed by the present invention are not particularly new, although the solution offered herein is believed novel. Others have attempted to formulate a solution, including Mr. Morrow in his recently issued U.S. Pat. No. 5,927,147, which addresses and successfully resolves, gear loading problems in a specific environment not related to the present circumstances.
In the 20""s and continuing into the 30""s, it appears that Westinghouse Electric was heavily involved in the construction of large transmissions for use in sea going ships and the like, and the balancing of loads from multiple power sources was of considerable concern. It appears from the patent art that the floating frame concept was prevalent at the time for balancing loading from multiple input sources, as evidenced by the Hodgkinson U.S. Pat. Nos. 1,502,199 and 1,591,826, coupled with Allen U.S. Pat. No. 1,502,224, all of which disclose a framework within which driving pinions are mounted for some limited movement to balance loading on them.
This observation is relevant only to explain the environment within which Herr U.S. Pat. No. 1,820,740 appears to have exclusive utility. Herr employs floating frames within which drive pinions are retained. A lever 40 is disposed between the frames and is flanked by flexible members and constrained by bolts on either side of the flexible members. A member disposed between the floating frames separates them and is pinned at one end to a fulcrum that allows limited movement and at the other end by a piston which constrains movement, except to a very limited extent. While Herr facially has an appearance similar to the present structure, that is where the similarity ends. As will be seen in Herr, and the art similarly situated, pressure exerted on the member disposed between the movable frames, by one of the frames, results in the opening and/or closing of the valves to apply fluid pressure at one end thereof, causing counter movement of that member to restore balance to the frames.
While there is an abundance of prior art directed at the general concept of balancing loads on gears, and more particularly helical gears, there is a paucity of such art wherein input loading is divided among pairs of intermediate transmission paths and wherein load balancing is achieved by sensing reactive forces on associated pairs of intermediate transmission elements and responding to those forces by balancing them in order that the load transmitted by such elements is uniform to the output of the transmission.
As will become apparent from a further reading of this specification, while the art referenced seems to recognize a similar, albeit not the same, problem and offers several solutions involving a movable gear or pinion, the invention taught herein represents what is believed to be a significantly and patentably different approach to the problem articulated above.
Having explored the environment in which the present invention has particular, although perhaps not exclusive, utility, it will now be appreciated that the geared transmission of the type addressed herein comprises, in one form, one or more pairs of helical gear sets, typically on parallel shafts, in operative engagement with a power input source, and capable of delivering the power therefrom in a uniform balanced manner to the transmission output.
Clearly, therefore, a principal objective of the present invention is to provide a transmission of the type having a power input and pairs of intermediate elements engaging the input to split the power therefrom and deliver that power in a uniform and balanced manner to the transmission output.
A further objective, incident to the foregoing, is to provide such a transmission which can deliver significant power from a single source to a driven member in an efficient and economical manner, with minimal wear and tear on the components which define the transmission, and to accomplish this in a package which is smaller than would otherwise be anticipated given the load parameters.
Yet another objective of the present invention is to provide for the positive and continuous mechanical balancing of loads on pairs of intermediate transmission elements which are in driving engagement with an input source by sensing imbalance between intermediate geared elements and continuously loading the element of a pair of elements which is not carrying as much load as its companion, and accomplishing this instantaneously to achieve continuous balance between and among pairs.
While the foregoing delineates several significant and practical objectives attainable by the structure of the invention, no effort has been made to articulate all of the objectives that are met by the gear set of the present invention, and others will become apparent to those skilled in the art as the forthcoming description of a preferred embodiment is studied, in conjunction with the appended drawings, wherein: